Controllable pitch propeller system

ABSTRACT

A controllable pitch propeller assembly wherein the pitch of the blades is controlled by an hydraulically actuated piston and cylinder assembly. Auxiliary hydraulic supply means are provided for actuating the piston and cylinder assembly in the event the primary hydraulic supply fails.

United States Patent Liaaen 1 Feb. 8, 1972 [54] CONTROLLABLE PITCHPROPELLER SYSTEM [72] Inventor: Anders M. Liaaen, Alesund, Norway [73]Assignee: A. M. Liaaen A/S, Alesund, Norway [22] Filed: Mar. 27, 1970[21] Appl. No.: 23,172

[30] Foreign Application Priority Data Mar. 28, 1969 Norway...'..1311/69 US. Cl. ..416/157 ..B63h 3/08 FieldofSearch ..416/l57,31, 162,156, 48,

[56] References Cited UNITED STATES PATENTS 2,312,686 3/1943 Campbell..91/33 X 2,693,243 11/1954 Strandell et a1 ..416/157 2,802,453 8/1957Harp et a1. ..91/33 X 2,830,668 4/1958 Gaubis et a1 ..416/157 FOREIGNPATENTS OR APPLICATIONS 1,266,846 6/1961 France ..416/157 PrimaryExaminer-Everette A. Powell, Jr. Au0rneyWatson, Cole, Grindle & Watson[57] ABSTRACT A controllable pitch propeller assembly wherein the pitchof the blades is controlled by an hydraulically actuated piston andcylinder assembly. Auxiliary hydraulic supply means are provided foractuating the piston and cylinder assembly in the event the primaryhydraulic supply fails.

5 Claims, 8 Drawing Figures PATENTEB EB 81912 3.840.644

SHEET 1 BF 4 1 I V I INVENTOR O NEY PATENIEIJFEB 8 SHEET 2 BF 4 FIG. 3.

INVENT BY W7.

/ ATTORNEY PAIENIEDFEB 8 I972 3, 640.644

sum 3 or 4 FIG. 5.

INVENTOR PAIENTEDFEB 8|872 3, 40,544

SHEET '4 UP 4 293 291 FIG. 7.

J 25 2a 6 I 273 21 13 292 r y" 22 72 22 INVENTORY.

C ONTROLLABLE PITCH PROPELLER SYSTEM The present invention relates to acontrollable pitch propeller system, in particular adapted for use inseagoing vessels, of the type wherein the angular adjustment of thepitch of the propeller blades is controlled by a hydraulic servomotorsystem, from a pressure fluid source, such as a pump, possibly with asimilar source in reserve. The servomotor system comprises, ordinarily,a cylinder and piston system, in which the piston rod is connected tothe root of each of the propeller blades, so that the blade pitchdepends upon the position of the servomotor piston in its cylinder. Thisposition is determined by the supply of pressure fluid to either side ofthe piston in the cylinder, and such supply usually is controlled bymeans of a distribution slide valve and is effected through conduitsextending axially in the propeller shaft. Customarily, the servomotor ispositioned in the propeller shaft or in the propeller hub proper, and soarranged that a movement of the servomotor piston forwardly in thefore-and-aft direction of the vessel will cause an adjustment of theblade pitch in a direction for forward movement of the vessel, but it isalso possible to so arrange matters that a forward adjustment of thepropeller blades depends upon a rearward movement of the servomotorpiston.

As mentioned, it is customary to provide a reserve pressure fluid sourcefor the purpose of securing the operation of the servomotor system. Thefact is that if a failure occurs in the pressure fluid supply, thepropeller blades, due to the movement of the vessel forwardly throughthe water, will tend to turn into a position for rearward movement. Theconsequence is that the vessel looses its steering, and it is thereforeof decisive importance that a failure in the pressure fluid supply beprevented. The provision of a reserve pressure fluid source will remedya failure in the external supply. For the purpose of overcoming afailure in the immediate vicinity of, or in the distribution slide valveproper, or due to leakage in the introduction means, it has beensuggested and used, systems of springs or hydraulic piston systemswhich, in case of failure, seek to cause the propeller blades to adopt apermanent position for forward movement. Such systems, which are adaptedfor direct, mechanical control of the servomotor must, necessarily, berather strong, in order to overrule both friction in the interior of thepropeller hub and the natural tendency, referred to, for rearwardadjustment of the propeller blades, and they will also influence theordinary operation of the entire propeller system.

The object of the present invention is a variable pitch propeller systemof the type referred to above, wherein the structural and functionalinconveniences of the previously known systems are avoided, theservomotor piston being subjected to no influence different from thatpresent under ordinary operation.

According to the invention, the variable pitch propeller systemcomprises a means which, in emergency cases closes the line whichordinarily conveys pressure fluid to that side of the servomotor pistonwhich induces forwardly adjustment of the propeller blades, andsimultaneously opens a connection to an emergency supply of pressurefluid. Thus, in the operation of such a system, the servomotor piston,at a failure anywhere in the ordinary supply of pressure fluid, will beswitched over from the ordinary pressure fluid source, possibly areserve source, to an emergency source, independently of the ordinarydistribution and introduction means, and the servomotor and adjustmentmeans are continuously in condition for operation in the same manner asin ordinary operation.

According to the invention, the switching means comprises a floatingpiston, the rod of which, which is hollow, is adapted to simultaneouslyclose the ordinary supply line of the pressure fluid to the servomotorspace inducing forwardly adjusting of the propeller blades and to openconnection between the said space and an emergency pressure fluidsource.

For the resetting of the piston of the emergency slide valve means tothe position to be adopted by the piston under normal operationalconditions, the piston may be formed as a stepped piston, having onestep surface adapted to be subjected to pressure from the ordinarypressure fluid supplied through the line for adjusting the servomotorpiston for forward movement.

For the purpose of securing that the opening of the ordinary supply ofpressure fluid be closed prior to the opening of the ordinary supply ofpressure fluid be closed prior to the opening of the supply of emergencyfluid, it is convenient to provide a phase displacement device, therebythat the hollow piston rod initially is guided on a stationary centralprojection, the length of which is such that the piston must have moveda certain distance before connection between the supply side of thepiston and the hollow piston rod be opened.

When the servomotor piston is set in position for forward movement bymeans of an emergency setting means, for instance in the manner of thepresent invention, it is convenient to provide that the servomotorpiston be locked in this position, so that the piston will remain inposition for full forward movement. For this purpose, the servomotorcylinder may be provided, in front of the piston, with a sealing meanswhich in cooperation with the piston is adapted to seal the piston whenthis reaches the position in which the sealing means is arranged. Thiscooperation may be facillitated by the provision of a charnferedcircumferential surface on the forward end face of the piston, so thatthe sealing means will be wedged in between this surface and thecylinder wall. It is a fact that the ordinary piston rings will notprovide perfect sealing, so that the piston may creep rearwardly,thereby necessitating one or more emergency setting, which obviously isnot desirable.

In the accompanying drawings, two embodiments of the system according tothe invention are schematically illustrated, viz one embodiment in whicha forward adjustment of the propeller blades corresponds to a forwardlydirected movement of the servomotor piston, and one in which suchadjustment corresponds to a rearwardly directed movement of the piston.

The first embodiment is shown in the FIGS. 1 to 4.

FIG. 1 is an axial fore-and-aft sectional view of the portion of thepropeller shaft comprising conduits for the supply and withdrawal ofpressure fluid to and from respectively the servomotor which controlsthe propeller blade pitch.

FIG. 2 is an axial fore-and-aft sectional view of the propeller hub, andis to be presumed to be a left-hand continuation of the shaft portionshown in FIG. 1.

FIG. 4 is a detail view from FIG. 2, also in axial section.

The second embodiment is shown in the FIGS. 5 to 8.

In these FIGURES, the same reference numerals are used as in the FIGS. 1to 4, applied to parts which correspond to each other, the onlydifference between the two embodiments being that the servomotor pistonis moved in a rearward direction when forwardly adjusting the propellerblades.

FIG. 5 corresponds to FIG. 1, FIG. 6 to FIG. 2, FIG. 7 to FIG. 3 andFIG. 8 to FIG. 4.

As shown in the drawings, the system comprises in both embodiments apropeller hub I in which there is mounted a number of propeller blades 2which may be turned in the hub 1 from settings for forward movement ofthe vessel to settings for rearward movement, and vice versa, by meansof a crank head device 3, the setting of which is controlled by means ofa servomotor which is mounted in the propeller hub l and comprises acylinder 4 with piston S. The setting of the piston 5, and thereby theangular setting (pitch) of the propeller blades 1 is controlled by meansof a pressure fluid which is supplied to either side of the piston 5through pipe lines accommodated in the hollow shaft 6, from an externalpressure fluid source, merely indicated by its inlet openings 12 and 13,FIGS. 3 and 7.

A cylindrical portion 7 of the shaft 6 is freely rotatable in astationary fluid introducing casing 8, accommodating a slide member 9which is axially slidable. The casing 8 is provided with an inletopening 10 for pressure fluid, and two outlet openings 1 1 leading to asump, not shown. The casing 8 is also provided with the inlet openings12 and 13 referred to above, leading to the spaces to either side of theservomotor piston 5, through conduits accommodated in the shaft 6through a tube 14, and through a tube 15, respectively, the tube 15being centrally and axially mounted in a central bore in the shaft 6.

The slide member 9 is controlled in conventional manner under the use ofa resetting means which comprises a ring 16 connected to rods 17 whichare connected to a yoke 18 on the tube 14, the rearward (left-hand) endof which is secured to the hollow piston rod 20 of the piston 5 and theforward (right-hand) end is slideable with close fit. The piston rod 20is the member which moves the crank head 3 for the adjustment of thepitch of the propeller blades 1.

The part of the system described so far, does not per se, form any partof the present invention.

In the system shown in the FIGS. 1 to 4, the bore in the shaft 6comprises a large portion 21, extending from a forward (right-hand)point to a point situated between the inlet openings 12 and 13. Theportion 21 is closed against a narrower portion of the bore between theopenings 12 and 13, by means of a ring 22 which is provided with anopening 220 corresponding to the opening 13 in the casing 8. The ring 22is provided with a central opening accommodating the tube 15 with closefit, the tube 15 terminating in an open end forward (to the right) ofthe ring 22.

The forward portion of the large portion 21 is provided with a portion23 with a slightly greater diameter, and is closed in a flange 24 at theright-hand end of the shaft 6 by means of a plate 25 provided with acentral, sleeve formed projection 251 extending rearwardly from theplate 25 and having a chamfered end surface 252.

In the portion 23 of the bore 21, there is provided a floating piston 26having a hollow piston rod 27 of which a forward, thick portion 271 isdisplaceable with close fit in a stationary bushing 28 in the bore 21,and a rearward, thinner portion 272 displaceable with close fit in acylindrical extension 221 of the ring 22. In this extension 221, thereare provided axial grooves 222, so that the space of the bore 21surrounding the piston rod 27 is communicating with the bore 13, to theeffect that the position of piston 26 shown in the top part of FIG. 3,fluid is flowing from the opening 13 into the bore 21, both around andin the interior of the piston rod 27. The length of the projection 251on the disc is so chosen relatively to the stroke length of the piston26, 27, that when the piston rod 27 engages the ring 22 in the rearward,left-hand position of the rod, there will be a free flow section pastthe end surface 252, between the space on the front side of the piston26 and the space inside the piston rod 27.

In the connecting flange 24 at the forward end of the propeller shaft 6,there is provided a radial bore 29 which is screw-threaded at 291 at theouter end. In ordinary operation, the bore 29 is closed by a pin 292which is provided with a screw-threaded head 293 and with an air passage294.

In the forward position of the piston 26, the bore 29 opens into thespace 23 at the front side of the piston 26.

The flange 24 is also provided with an air passage 31 which opens intothe space of the bore portion 23 at the rear side of the piston 26, andwhich may be closed by means of a plug 32 in the flange 24.

The forward end of the servomotor cylinder is provided with a U-formedjoint 30, as shown at a greater scale in FIG. 4, and the forward end ofthe piston 5 is chamfered at 51. One lip 301 of the joint extendssomewhat into the free space in the cylinder 4, so as to engage thechamfered end of the piston 5 when the same is moved to a forward endposition, and to slide upwardly along the circumferential surface of thepiston 5.

In the embodiment of the system according to the invention which isshown in the FIGS. 5 to 8, the arrangement is, as mentioned, such thatthe servomotor piston 5 is moved rearwardly, to the left in the drawingin its cylinder 4, when the propeller blades are to be adjusted towardsahead movement of the vessel. Consequently, the joint 30 and thechamfered end 51 of the piston are here situated in the rearward,left-hand end of the cylinder 4. The disposition of the auxiliary piston26 is therefore reversed relatively to the disposition shown in theFIGS. 1 to 4, i.e., arranged in the left-hand connecting flange 24 ofthe shaft 6, instead of in the right hand flange 24.

In this case the communication between the tube 14 and the opening 12which is to be broken and replaced by a connection to an emergencysource, through the bore 29. Structurally, this amended arrangementinvolves that the tube 14 is in slide fit engagement in the projection251, while the tube 15, in this case also, is in slide fit in the ring22.

The remaining details of this second embodiment are in completeaccordance with those of the embodiment shown in the FIGS. 1 to 4,described above.

The system of the invention operates in the following manner:

In ordinary operation, the openings 12 and 13 are communicating with anextension pressure fluid source, and by a suitable displacement of slidemember 9, such fluid is directed to the front or back side of theservomotor piston 5, for the purpose of adjusting the pitch of thepropeller blades 2 to rearward and forward movement, respectively of thevessel. In such ordinary operation, the system functions in a well-knownmanner, so that a closer description of the system and its functions isconsidered not to be required by a man skilled in the an.

If now a failure or breakdown should occur in connection with the inletcasing 8, or in the supply of pressure fluid from the main or emergencysource, the propeller blades will tend to change their pitch to aposition for rearward movement of the vessel, to the effect that thevessel will loose its steering. This inconvenience is overcome by meansof a system according to the present invention, in the following manner:

The pin 292 is screwed out of its bore 29, and a hose leading to anypressure fluid source is screwed into the threads 291. At the same time,the bore 31 is opened by removal of the plug 32.

When now the pressure fluid is introduced through the bore 29, thepiston 26 is moved to the left in FIG. 3 and to the right in FIG. 7, soas to adopt the position shown in the lower part of FIG. 3 and FIG. 7,respectively, with the piston rod 27 in engagement with the ring 22.Thereby, the communication between the opening 13 and the space insidethe piston rod 27 is broken and so also the communication to the tube14, while a free path is established from the bore 29, through the spaceon the front side of the piston 26, the space inside the piston rod 27,the tube 15 to the rear side of the servomotor piston 5, so that thelatter is so displaced that the propeller blades 2 are adjusted to asetting for full forward movement.

Hereby, the cylinder 4 and the ordinary adjustment mechanism are sodimensioned relatively to each other that the piston 5, in ordinaryoperation, will not attain its extreme position in the cylinder 4.Through the influence of the pres sure fluid through the bore 29, thepiston 5 is moved to its extreme, foremost or rearmost, respectively,position, in which the lip 301 of the seal 30 will enter the chamferedportion 51 of the piston 5 and engage the cylindrical circumferentialsurface. In this manner, it is prevented that any leakage of pressurefluid may occur from the rearside of the piston 5 with the consequentaltendency of the piston 5 to sag rearwardly. With the piston in thisextreme position and consequently with the propeller blades 2 in extremeforward setting, the supply of pressure fluid through the bore 29 isdiscontinued and the bore 29 is closed with a sealing pin or by anonretum valve.

The propeller blades 2 are now set in an extreme forward position. Thevessel has full steering capacity, just like a vessel provided withpropeller with a constant blade pitch, nd the steering may be effectedby means of the propulsion motor, in a fully ordinary manner.

When the failure in the ordinary pressure fluid supply is repaired, theplug 32 is again removed from the bore 29 and pressure is again suppliedthrough the opening 13. This pressure will be transmitted through thegrooves 222 and act upon the surface 273 which defines the thickestportion 271 of the piston rod 27 as against the thinner portion 272, sothat the piston 26 is pushed towards forward position, until readoptingthe position shown in the top portion of FIGS. 3 and 7, and ordinaryoperational condition is reestablished. When the piston 26 has reachedits forward end position, the pin 291 is again put into its place, andthe opening 31 is closed by means of the plug 32. If difficulties aremet in the returning of the stepped piston 27 to the extreme forwardposition, pressure is again introduced through the bore 31. Thispressure will influence the rear side of the piston 26 and push thepiston towards its end position.

In the embodiment shown in the FIGS. 1 to 4, it is presumed, asmentioned above, that the servomotor piston is to move in the forwarddirection, to the right in the drawing, when the propeller blades are tobe turned towards a forward setting. The auxiliary piston 26 is thenpositioned forward of the servomotor system.

However, if the servomotor system is of the type wherein an adjustmentof the propeller blades towards a forward position is caused by arearward, to the left, movement of the servomotor piston 5, theauxiliary system is positioned rearwardly of the casing 8, as shown inthe FIGS. 5 to 8.

I claim:

1. Controllable pitch propeller mechanism comprising:

a hollow, rotatable shaft;

a propeller hub mounted on one end of the shaft for rotation therewith;

a plurality of elongated propeller blades mounted on said hub andextending radially outwardly therefrom, said blades being rotatableabout their longitudinal axes relative to said hub;

a first piston and cylinder assembly disposed within said shaft adjacentsaid hub, said first assembly including a cylinder extendinglongitudinally of the shaft and having a pair of longitudinally spacedfluid ports communicating with the interior thereof, and a pistondisposed between said ports for movement longitudinally of the cylinder,said piston being operably connected to said blades for rotating thelatter about their longitudinal axes during said movement of the piston;

a pressure fluid supply system including a source of pressurized fluidand a fluid return;

valve means operable intereommunicating said fluid supply system and theports of the piston and cylinder assembly, said valve means beingoperable for alternatively connecting either of said ports with saidsource of pressurized fluid while simultaneously connecting the other ofsaid ports with said fluid return, there being a fluid passagewayextending between each of said ports and said valve;

a slide valve assemblage comprising a second cylinder and pistonassembly disposed in the propeller shaft, said second assemblycomprising a piston member movable axially of said shaft between twoextreme positions, said member being provided with a hollow cylindricalskirt having an open end extending toward and opening into one of saidpassageways, said skirt being disposed, when said piston member is inone of its extreme positions, to block said one passageway between saidvalve means and the hollow space within said skirt with the latterremaining in fluid communication with said passageway and its port,

the cylinder of the second assembly being provided with an inletcommunicating with the cylinder space on the side of the piston memberremote from said passageway, said inlet being connectable to a secondsource of pressurized fluid, said second assembly including passagedefining means disposed for intercommunicating said cylinder space withsaid hollow space of the piston member when the latter is in said oneextreme position.

2. Mechanism as set forth in claim 1 wherein said piston member has astepped configuration presenting an annular piston face on the externalsurface thereof facing a space communicating with said blockedpassageway between the piston member and the valve means.

3. Mechanism as set forth in claim 1 wherein the cylinder of the slidevalve assemblage has an end wall provided with a centrally protrudingportion, said piston member having a central bore disposed at theopposite end thereof from said skirt, said protruding portion beingdisposed and configured to cooperate with said central bore to closesaid cylinder space during the initial movement of the piston memberunder the influence of fluid from said second source.

4. Mechanism as set forth in claim 1 wherein the cylinder and piston ofthe first assembly are provided with interengaging sealing members forsecuring and sealing said piston when the latter is in the position itassumes under the influence of pressure exerted through said onepassageway from said second source.

5. Mechanism as set forth in claim 4 wherein the sealing member of saidpiston comprises an annular, chamfered surface.

1. Controllable pitch propeller mechanism comprising: a hollow, rotatable shaft; a propeller hub mounted on one end of the shaft for rotation therewith; a plurality of elongated propeller blades mounted on said hub and extending radially outwardly therefrom, said blades being rotatable about their longitudinal axes relative to said hub; a first piston and cylinder assembly disposed within said shaft adjacent said hub, said first assembly including a cylinder extending longitudinally of the shaft and having a pair of longitudinally spaced fluid ports communicating with the interior thereof, and a piston disposed between said ports for movement longitudinally of the cylinder, said piston being operably connected to said blades for rotating the latter about their longitudinal axes during said movement of the piston; a pressure fluid supply system including a source of presSurized fluid and a fluid return; valve means operably intercommunicating said fluid supply system and the ports of the piston and cylinder assembly, said valve means being operable for alternatively connecting either of said ports with said source of pressurized fluid while simultaneously connecting the other of said ports with said fluid return, there being a fluid passageway extending between each of said ports and said valve; a slide valve assemblage comprising a second cylinder and piston assembly disposed in the propeller shaft, said second assembly comprising a piston member movable axially of said shaft between two extreme positions, said member being provided with a hollow cylindrical skirt having an open end extending toward and opening into one of said passageways, said skirt being disposed, when said piston member is in one of its extreme positions, to block said one passageway between said valve means and the hollow space within said skirt with the latter remaining in fluid communication with said passageway and its port, the cylinder of the second assembly being provided with an inlet communicating with the cylinder space on the side of the piston member remote from said passageway, said inlet being connectable to a second source of pressurized fluid, said second assembly including passage defining means disposed for intercommunicating said cylinder space with said hollow space of the piston member when the latter is in said one extreme position.
 2. Mechanism as set forth in claim 1 wherein said piston member has a stepped configuration presenting an annular piston face on the external surface thereof facing a space communicating with said blocked passageway between the piston member and the valve means.
 3. Mechanism as set forth in claim 1 wherein the cylinder of the slide valve assemblage has an end wall provided with a centrally protruding portion, said piston member having a central bore disposed at the opposite end thereof from said skirt, said protruding portion being disposed and configured to cooperate with said central bore to close said cylinder space during the initial movement of the piston member under the influence of fluid from said second source.
 4. Mechanism as set forth in claim 1 wherein the cylinder and piston of the first assembly are provided with interengaging sealing members for securing and sealing said piston when the latter is in the position it assumes under the influence of pressure exerted through said one passageway from said second source.
 5. Mechanism as set forth in claim 4 wherein the sealing member of said piston comprises an annular, chamfered surface. 